Skin examination by physicians is a widely used procedure aimed at timely determining various abnormalities on a patient's skin, in order to identify a skin disease or timely detect a condition indicative of possible development of a disease. For example, melanoma is a highly malignant tumor that starts when melanocytes produce black to yellow pigments color in normal skin or moles (nevus). Melanoma has doubled in incidence in recent decades and is increasing more rapidly than any other cancer. Melanoma metastasizes rapidly and widely. Early detection of a skin lesion as melanoma is a key factor in improving patient survival and decreasing treatment costs. About 3 million moles are evaluated by biopsy each year in the United States, and of those over 60,000 are diagnosed as melanoma that end in more than 8,000 deaths.
A number of optical techniques for identifying abnormal tissues and prevent unnecessary biopsies have been recently developed. Some of these optical techniques make use of multispectral digital dermatoscopy. According to these techniques, quantitative data are generated with sequences of images of skin lesions taken at different wavelengths of incident light. Image processing can be used by a clinician to decide whether the lesion should be biopsied or not. More specifically, the known used technologies include MoleMate and MelaFind techniques. The SIAscope MoleMate is a chromophore imaging system that probes 1 cm2 to 2 cm2 areas of skin using wavelengths of 400 nm to 1000 nm. Spectrally-filtered images are obtained and respective data is processed to determine the micro-architecture of the skin. SIAscopy measures the amount of collagen, hemoglobin, melanin, and melanin distribution in the epidermis and dermis. This information is presented in the form of maps called SIAscans, which are then interpreted by the clinician. MoleMate incorporates SIAscopy in a diagnostic algorithm specifically developed for use by primary care physicians. As with conventional dermatoscopy, diagnostic accuracy of the SIAscope depends on the experience of the physician interpreting the SIAscans. In addition, hyperkeratosis in seborrheic keratoses can be interpreted as dermal melanin, giving false positive results. MelaFind acquires 10 images for lesions that encompass the visible and near-infrared spectrum. Six scores are generated for each lesion based on constrained linear classifiers, with each classifier trained to differentiate melanoma from other pigmented lesions. A lesion is then recommended for biopsy if all six scores are above the threshold value. MelaFind has low specificity for melanoma detection.
Multiwavelength ultraviolet-visible spectrophotometry is a powerful tool for the characterization of biological tissues. With the acquisition of a spectrum of blood cells, it is possible to obtain information on parameters such as reflectance property, metabolism and chemical composition. Application of this technology coupled with spectral interpretation using the theory of light scattering allows for the analysis of cells. The method is known as particularly useful in the examination of reflectance properties of the target. Furthermore, the opportunity to examine the spectrum over a large wavelength range (190 nm-1100 nm) allows for redundant analysis through mathematical corroboration of all wavelengths, providing a high level of reliability of the elucidated values.
WO 01/24699 and its counterpart U.S. Pat. No. 7,280,866 disclose a non-invasive tool for skin disease diagnosis. In-vivo visible- and near-infrared spectra (400-2500 nm) of skin neoplasms (actinic keratoses, basal cell carcinomata, banal common acquired melanocytic nevi, dysplastic melanocytic nevi, actinic lentigines and seborrheic keratoses) were collected by placing a fiber optic probe on the skin. Paired t-tests, repeated measures analysis of variance and linear discriminant analysis were used to determine whether significant spectral differences existed and whether spectra could be classified according to lesion type. Paired t-tests showed significant differences (p<0.05) between normal skin and skin lesions in several areas of the visible/near-infrared spectrum. In addition, significant differences were found between the lesion groups by analysis of variance. Linear discriminant analysis classified spectra from benign lesions compared to pre-malignant or malignant lesions with high accuracy.
WO 98/46133 discloses an apparatus for diagnosis of a skin disease site using spectral analysis. The apparatus includes a light source for generating light to illuminate the disease site and a probe unit optically connected to the light source for exposing the disease site to light to generate fluorescence and reflectance light. The probe unit also collects the generated fluorescence and reflectance light and transmits this light to a spectrometer to be analyzed. The spectrometer generates and displays spectral measurements of the fluorescence light and the reflectance light which in together assist the user in diagnosing the disease site. The apparatus makes use of a conventional personal computer using a plug-in spectrometer card to provide a compact and low costs system. The system performs combined fluorescence and reflectance spectral analysis in a quick and efficient manner to provide a powerful tool for dermatologic diagnosis.